North Sea oil producer Serica Energy will deepen its interest in two of the North Sea’s most important oil and gas assets in a deal to buy holdings from French major Total. The $20m (£15.4m) acquisition of Total’s stakes in the Bruce and Keith oil assets has emerged as Serica battled to push through a separate plan to buy BP’s stakes in the same fields, which has been mired by US sanctions due to another asset in the deal being partly owned by an Iranian company.